1. Field of the Invention
The invention relates to the formation of thin film conductive interconnections between electronic components and in particular to the formation of interconnections having negligible parasitic capacitance and inductance.
2. Description of the Prior Art
In semiconductor device fabrication it is often necessary to interconnect electronic components on a chip in such a manner as to minimize the parasitic reactance of the interconnection conductors. This is especially true when the chips are to be utilized in high frequency applications such as microwave amplifiers and digital processors.
To minimize capacitive reactance it is common practice to route the conductors so as to minimize the number of crossings thereof and to maximize the distance between crossing conductors by using an arched wire for the crossover conductor. This practice frequently results in circuitous routing of conductors, which uses up valuable chip area. Additionally, the arched wire is relatively thick in comparison with conductors that can be formed on the chip by thin film techniques and is a source of parasitic inductance.
One connection technique which results in low parasitic reactance of both types and makes efficient use of chip area is that of forming air bridges at crossover points. Thus, rather than routing conductors to avoid crossing, the thin film conductors on the chip are routed directly between the components to be interconnected thereby and these conductors are spaced from conductors which they cross by an air gap. Because of the low dielectric constant of air in comparison to the solid insulating materials normally used between crossing thin film conductors, the capacitance at these air-spaced crossovers is negligible.
Although this connection technique is generally known in the art, simple methods for forming high strength air bridges are not. It is therefore an object of the present invention to provide simple methods for forming such air bridges.